• 한국터널지하공간학회 논문집
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• 제20권5호
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• pp.855-867
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• 2018

터널 굴진면 전방에 연약대가 존재할 때에는 종방향 아칭에 의해서 굴진면 직전영역에 응력이 증가되어 터널의 안정성이 영향을 받는다. 따라서 굴진면 전방에 연약대 존재 여부 및 연약대의 특성을 파악하여 이에 대한 대비책을 마련하는 것이 중요하다. 굴진면 전방 연약대의 예측 방법은 물리탐사 및 수치해석적 방법과 터널지보 및 보강방안에 대한 연구는 많이 이루어 졌으나 굴진면 전방 연약대의 폭과 이격거리에 따른 이완영역에 대한 연구는 미비한 실정이다. 본 연구에서는 굴진면 전방에 연약대 존재 시 연약대의 폭과 이격거리에 따른 이완영역에 대하여 실내모형실험을 통해 규명하였다. 모형시험기에 주문진 자연사를 이용하여 함수비 3.8%로 모형 원지반을 조성하였으며 모형 연약대는 모형 원지반과 같은 자연건조 상태의 주문진 자연사를 샌드커튼 방식으로 강사하여 조성하였다 연약대 폭과 굴진면과 연약대 간 이격거리를 변화시키며 실험을 수행하였다. 모형시험기는 상하반단면 굴착이 구현 가능하도록 제작하였으며, 토조 바닥에 로드셀을 설치하고 지표에 변위계를 설치하여 터널굴착에 따른 연직응력 및 지표변위를 측정하였다. 지표침하는 연약대의 폭에 상관없이 굴진면과의 이격거리가 0.25D 이내에서 급격히 증가하였고, 수직응력 및 수평응력 또한 이격거리가 0.5D 이내에서부터 증가하는 경향이 나타났다. 실험결과 종방향 아칭의 영향은 터널 전방 1.0D 영역 내부터 형성된다고 판단된다.

• 환경영향평가
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• 제21권5호
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• pp.781-787
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• 2012

The purpose of this study was to analyze the landscape changes at Su-ji and Gi-heung in Young-in city using FRAGSTATS Model. Landscape Indices obtained by this model can explain the structural change of urban green zone and fragmentation resulting from development. As results of this study, Gi-heung showed worse quality of landscape in 2007, comparing 2000. However, in Su-ji, there were several better landscape indices in the same 2007/2000 comparison, even though the little shrinking of green zone and separation of core area. It could assume that the reason was caused by conservation policy of urban green zone. This study could provide the useful methods for finding the problems and searching the alternatives considering the development of urban green zone.

• 한국연소학회지
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• 제13권1호
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• pp.31-43
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• 2008

Oxy-fuel flame has a significantly different structure from that of air-fuel flame because of its high temperature. This study is aimed to find out the difference of the oxy-fuel flame structure in order to understand reaction mechanism closely, which is crucial to design real-scale oxy-fuel combustion system. By examining pictures of counterflow flame and LIF images, we found that oxy-fuel flame had two-zone structure: fuel decomposition region and distributed CO oxidation region. In the oxy-fuel flame, OH radical was distributed intensely through the whole flame due to its higher flame temperature than crossover temperature. For showing those features of the oxy-fuel flame, 1 MW scale IFRF oxy-natural gas burner was simulated by conditional moment closure(CMC) model. Calculation results were compared with experimental data, and showed agreements in trend. In the simulated distributions of fuel decomposition/CO oxidation rates, CO oxidation region was also separated from fuel decomposition zone considerably, which showed the two-zone structure in the oxy-fuel flame.

• 정보처리학회논문지C
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• 제11C권1호
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• pp.81-88
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• 2004

본 논문에서는 다중 VPN을 수용하는 대규모 네트워크에서 인터넷 액세스를 지원할 때, 보안 정책에 따라 신뢰구역(Trust zone)의 불확실한 경계설정으로 발생할 수 있는 보안 문제를 해결하기 위한 적응방안을 제시하였다. 관련연구로 기존 적용모델과 다중 VPN 네트워크에서의 보안 위협을 분석하고, 외부 네트워크로부터의 보호를 위해 신뢰구역 분리와 분산 정책 적용을 고려한 시뮬레이션을 수행하였다. 시뮬레이션을 통해 다중 VPN 수용과 인터넷 액세스에 의한 신뢰구간의 불확실한 경계는 신뢰되지 않은 경계로부터의 분산 계층적인 Perimeter defence 정책 적용을 통해서 개별 VPN간의 신뢰구간을 축소할 수 있었고, 하위 개별 사이트로부터의 적용보다 정책 적용횟수가 줄어 전송 지연에 영향을 줄일 수 있었다.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.929-944
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• 2009

The present study is concerned with the extension of the Effective Convectivity Model (ECM) to the phase-change problem to simulate the dynamics of the melt pool formation in a Light Water Reactor (LWR) lower plenum during hypothetical severe accident progression. The ECM uses heat transfer characteristic velocities to describe turbulent natural convection of a melt pool. The simple approach of the ECM method allows implementing different models of the characteristic velocity in a mushy zone for non-eutectic mixtures. The Phase-change ECM (PECM) was examined using three models of the characteristic velocities in a mushy zone and its performance was compared. The PECM was validated using a dual-tier approach, namely validations against existing experimental data (the SIMECO experiment) and validations against results obtained from Computational Fluid Dynamics (CFD) simulations. The results predicted by the PECM implementing the linear dependency of mushy-zone characteristic velocity on fluid fraction are well agreed with the experimental correlation and CFD simulation results. The PECM was applied to simulation of melt pool formation heat transfer in a Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) lower plenum. The study suggests that the PECM is an adequate and effective tool to compute the dynamics of core melt pool formation.

• 한국CDE학회논문집
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• 제10권6호
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• pp.432-443
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• 2005

Recent three-dimensional feature-based CAD systems based on solid or non-manifold modelling functionality have been widely used for product design in manufacturing companies. When product models associated with features are used in various downstream applications such as analysis, however, simplified and abstracted models at various levels of detail (LODs) are frequently more desirable and useful than the full detailed model. To provide multi-resolution models, the features need to be rearranged according to a criterion that measures the significance of the feature. However, if the features are rearranged, the resulting shape is possibly different from the original because union and subtraction Boolean operations are not commutative. To solve this problem, in this paper, the new concept of the effective zone of a feature is defined and identified using Boolean algebra. By introducing the effective zone, an arbitrary rearrangement of features becomes possible and arbitrary LOD criteria may be selected to suit various applications. Besides, because the effective zone of a feature is independent of the data structure of the model, the multi-resolution modelling algorithm based on the effective zone can be implemented on any 3D CAD system based on conventional solid representations as well as non-manifold topological (NMT) representations.

• 한국구조물진단유지관리공학회 논문집
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• 제4권2호
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• pp.113-129
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• 2000

This study evaluates the behavior and strength of an anchorage zone of the prestressed concrete box girder bridge on the Kyungboo highway railroad using the 2D SUB-3D STM approach and a linear elastic finite element analysis. The 2D SUB-3D STM approach utilizes several two-dimensional sub strut-tie models that represent the compressive and tensile stress flows of each projected plane of the three-dimensional structural concrete in the selection of a three dimensional strut-tie model, evaluation of the effective strengths of the concrete struts, and verification of the geometric compatibility condition and bearing capacity of the critical nodal zones in the selected three-dimensional strut-tie model. The finite element analysis uses an 8-node brick element and the longitudinal prestressing force is considered as the equivalent nodal force. Analysis results show that the 2D SUB-3D STM approach and linear elastic finite element method can be effectively applied to the analysis and design of three-dimensional structural concrete including a prestressed concrete box girder anchorage zone.

• 한국태양에너지학회 논문집
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• 제31권4호
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• pp.1-8
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• 2011

In this paper, inverse building modeling was applied to building perimeter zones which have different window orientation. Two test zones of east-facing and west-facing zones in ERS(Energy Resource Station) building, which is representative of small commercial building, was used to test performance of cooling load calculation and peak cooling load reduction. The dynamic thermal load model for the east and west zone was validated using measured data for the zones and then it was used to investigate the effect of peak cooling load reduction by adjustment of indoor cooling temperature set points during on-peak time period. For the east zone, the peak load can be reduced to about 60% of the peak load for conventional control even without any precooling. For the west zone, PLR is nearly independent of the start of the on-peak period until a start time of 1pm. Furthermore, PLR has a small dependence on the precooling duration. Without any precooling, the peak cooling load can be reduced to about 35% of the peak load associated with conventional control.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1136-1143
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• 2008

The Vertical Drains(Sand Drains, Pack Drain, PBD) is used for Vertical Drains Method in domestic. Each of the drains is selected after it consider a field condition and efficiency of drain. A discharge capacity is very important factor, which to estimate a efficiency. And the smear Zone where disturbance area of in-suit by installation of Vertical Drains is important factor to select a drains. In this study, the complex discharge capacity test was operated for discharge capacity comparison of the Wing Drain and PBD. And a model test was operated to apprehend smear zone of the Wing Drain and PBD. From these tests, it was apprehended an engineering characteristic of vertical drain. The results of the complex discharge capacity test, a discharge capacity fell below $20cm^3/sec$ to $1cm^3/sec$ in more than overburden load $2.5kg/cm^2$. The Wing Drain maintained a over $40cm^3/sec$ in more than overburden load $2.5kg/cm^2$ and minimum discharge capacity $8cm^3/sec$. The results of the smear zone test, a influence bounds of smear zone was more larger in case of the Wing Drain(rectangle) than the PBD. But when a discharge capacity of Wing Drain is considered, it was concluded which smear zone bounds difference was effected in comparison with PBD. I think that it minimized a mandrel section to minimize a smear zone effect range

• 대한교통학회지
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• 제33권6호
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• pp.575-583
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• 2015

한국교통연구원은 수도권 및 광역권의 기종점 자료를 읍면동 행정단위로 교통존을 세분화하여 배포하고 있으며, 지방부는 자료의 한계로 시군구 행정단위로 교통존을 구축하여 배포하고 있다. 도로 및 철도사업에서 사업 주변 지역에 정교한 통행 패턴을 분석하기 위해서 특정 교통존을 더욱 잘게 나누어 세분화된 교통존을 구축하는 과정이 필요한 경우가 있다. 본 연구는 시군구 행정단위의 지방부 교통존에서 읍면동 행정단위로 세분화된 교통존의 O-D 통행량을 추정하는 방법론을 제시하였다. 수도권 및 광역권의 공간적인 내부 통행 분포 패턴을 토대로 교통존의 인구 밀도를 저, 중, 고밀도 그룹으로 분류하고 그룹별 직접수요모형과 중력모형의 계수 값을 정산하였다. 그리고 회귀분석을 수행하여 내부 통행 분포 패턴을 잘 설명하는 모형을 최종적으로 선별하고 정산된 모형을 지방부에 적용하여 내부 교통존을 세분화한 교통존 간 통행량을 추정하였다. 분석 결과, power function을 저항함수로 정산한 중력모형의 수정된 $R^2$가 인구 저밀도 그룹에서는 0.7426, 중밀도 그룹에서는 0.6456, 고밀도 그룹에서는 0.7194로 산출되었으며 본 모형이 교통존 내부의 세부존 간의 통행 패턴을 우수하게 설명하는 것으로 분석되었다. 또한 본 연구에서는 강원도 인제군에 정산된 모형을 적용하여 세부존 간 통행량을 산출하는 예시를 제시하였다. 본 연구에서 제시한 세분화 교통존의 O-D 통행량 추정 방법론을 이용할 경우, 세분화된 교통존 간 통행량을 구축하여 통행 패턴을 좀 더 체계적이고 정교하게 분석할 수 있을 것이다.